Segmental mobility in poly(isoprene) rubber studied by deuterium-carbon NMR correlation spectroscopy

A HMQC based deuterium-carbon correlation method is used for the first time to study the segmental mobility in a fully deuterated poly(isoprene) (PI) rubber network. The isotropic J(CD) couplings can be utilized for polarizat ion transfer between H-2 and C-13 spins in a mobile solid polymer. This mak es it possible to correlate the H-2 resonances with the C-13 chemical shift s of tile attached carbon in a two-dimensional (2D) experiment, and thus al low the extraction of the individual H-2 signals. The experimental data obt ained from the 2D correlation spectrum indicates differences in the segment al mobility of the C-D vectors in perdeuterated Pi. The conclusions are ful ly consistent with H-2 and C-13 T-1 relaxation data. The results shown in t his paper demonstrate the potential of H-2-C-13 NMR correlation spectroscop y in solid systems which produce overlapped 1D H-2 spectra.